It is already known to manufacture, and use, heat curable pulverulent coating agents based on copolymers which contain glycidyl groups. However, such known products have the disadvantage that they have to be stoved at temperatures above 200.degree. C. to give resistant films.
If attempts are made to lower the stoving temperatures of such known pulverulent coating agents by addition of accelerators, the effect is inadequate or the films obtained yellow already during the stoving process; at times, the adhesion is also impaired.
Such known powder coating agents are described in German Published Specification Nos. 2,240,312, 2,240,314, 2,240,315, 2,057,577, 2,064,916, 2,214,650 and 2,122,313.
1. It is the object of the present invention to provide a heat-curable, pulverulent coating agent which simultaneously shows improvements in various directions compared to the known pulverulent coating agents. One aim is that it should be possible to manufacture the pulverulent agent by simple mixing, homogenising fusion and conjoint grinding of the requisite components.
2. The pulverulent coating agent manufactured by intensive mixing, homogenising fusion and grinding should be stable on storage at the customary storage temperatures of between about -40 to +40.degree. C.
3. The coating agent should, after application, given very glossy non-yellowing coatings, with good levelling properties and freedom from blisters and craters, merely by stoving at about 150.degree. to 180.degree. C. for about 15 to 30 minutes.
4. The stoved films should not yellow and should show excellent weathering resistance and substantially improved resistance to organic solvents and chemicals, the comparison being relative to powder lacquers based on acrylate copolymers.